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2017-06-05
Technical Paper
2017-01-1842
Akin Oktav, Cetin Yilmaz, Gunay Anlas
As a countermeasure to trunk lid slam noise, reactive openings are used in the trunk cavities of passenger vehicles. In sedans trunk and cabin cavities are coupled acoustically through discontinuities on the parcel shelf and/or the rear seat. In such a case, these openings behave as if necks of a Helmholtz resonator, which in turn change the acoustic response of the system, accordingly. The Helmholtz resonator effect of the trunk cavity is discussed analytically through a simplified cavity model. A case study is also given, where the acoustic response of a sedan is analyzed through the computational model that considers the resonator effect. Sound pressure level results show that instant pressure drops and damping effects observed in the acoustic response can be explained with the resonator effect. Results obtained from the computational model of the sedan are verified by road test measurements
2017-06-05
Technical Paper
2017-01-1775
Mark A. Gehringer, Robert Considine, David Schankin
This paper describes recently developed test methods and instrumentation to address the specific noise and vibration measurement challenges posed by large diameter single-piece tubular aluminum propeller shafts with high modal density. The application described in this paper is a light duty truck, although the methods described are applicable to any rotating shaft with similar dynamic properties. To provide a practical example of the newly developed methods and instrumentation, rotating and non-rotating data were acquired in-situ for several propeller shafts of varying construction, including both lined and unlined shafts. Data were also acquired with and without a torsional tuned vibration absorber attached to the driveline. The example data exhibit features that are uniquely characteristic of large diameter single-piece tubular shafts with high modal density, including the particular effect of shaft rotation on the measurements.
2017-06-05
Technical Paper
2017-01-1784
Guillaume Baudet
Automotive wind noise’s physic is complex : noise for passengers depend of : - acoustic transfer function in the cabin - transfer loss of seals and panels - first of all, exterior loading due to the flow around the vehicle For some years, we know that the exterior loading can and must be split in two parts : - Hydrodynamic (or turbulent) loading with high wave number pressure field - Acoustic loading with low wave number pressure field In simulation people start to separate the two pressure fields by complex signal processing. But in real life test, there is no simple method to do so. In this paper we present an inverse method, call “Panel Inverse Method” (PIM) which can extract the low wave number loading measured on a vehicle panel. The method may be known with the French “RIFF” name. It is based on acceleration measurement of the panel to calculate the pressure which create panel’s motion : that’s typically an inverse method.
2017-06-05
Technical Paper
2017-01-1859
Filip Franek, Jungu Kang, Jeon Uk, Sunguk Choi
Abstract: Structure-born vibrations are often required to be localized in a complex structure, but in such dispersive medium, the vibration wave propagates with speed dependent on frequency. This property of solid materials causes an adverse effect for localization of vibrational events. The cause behind such phenomena is the propagating wave envelope that changes its phase delay and amplitude in time and space as it travels in dispersive medium. This problem was previously approached by filtering a signal to focus on frequencies of the wave propagating with similar speed, what improved accuracy of cross-correlation results. However, application of this technique has not been researched for localization of vibrational sources by a localization technique. In this work we take advantage of filtering prior to cross-correlation calculation while using multiple sensors to indicate approximate location of vibration sources.
2017-06-05
Technical Paper
2017-01-1751
Nicolas Schaefer, Bart Bergen, Tomas Keppens, Wim Desmet
The continuous pursuit for lighter, more affordable and more silent cars, has pushed OEMs into optimizing the design of car components. The different panels surrounding the car interior cavity such as firewall, door or floor panels are of key importance to the NV performance. The design of the sound packages for high-frequency airborne input is well established. However, the design for the mid-frequency range is more difficult, because of the complex inputs involved, the lack of representative performance metrics and its high computational cost. In order to make early decisions for package design, performance maps based on the different design parameters are desired for mid-frequencies. This paper presents a framework to retrieve the response surface, from a numerical design space of finite-element frequency sweeps. This response surface describes the performance of a sound package against the different design variables.
2017-06-05
Technical Paper
2017-01-1760
Weimin Thor, J. Stuart Bolton
Due the increasing concern with the acoustic environment within an automotive vehicle, there is an interest in measuring the acoustic properties of automotive door seals. These systems play an important role in blocking external noise sources, such as aerodynamic noise and tire noise, from entering the passenger compartment. Thus, it is important to be able to conveniently measure their acoustic performance. Previous methods of measuring the ability of seals to block sound required the use of either a reverberation chamber or a wind tunnel with a special purpose chamber attached to it. That is, these methods required the use of large and expensive facilities. A simpler and more economical desktop procedure is thus needed to allow easy and fast acoustic measurement of automotive door seals.
2017-06-05
Technical Paper
2017-01-1788
Kishore Chand Ulli, Upender Rao Gade
Automotive window buffeting is a source of vehicle occupant's discomfort and annoyance. Original equipment manufacturers (OEM) are using both experimental and numerical methods to address this issue. With major advances in computational power and numerical modelling, it is now possible to model complex aero acoustic problems using numerical tools like CFD. Although the direct turbulence model LES is preferred to simulate aero-acoustic problems, it is computationally expensive for many industrial applications. Hybrid turbulence models can be used to model aero acoustic problems for industrial applications. In this paper, the numerical modelling of side window buffeting in a generic passenger car is presented. The numerical modelling is performed with the hybrid turbulence model Scale Adaptive Simulation (SAS) using a commercial CFD code.
2017-06-05
Technical Paper
2017-01-1807
Richard DeJong, Gordon Ebbitt
The SEA model of wind noise requires the quantification of both the acoustic as well as the turbulent flow contributions to the exterior pressure. The acoustic pressure is difficult to measure because it is usually much lower in amplitude than the turbulent pressure. However, the coupling of the acoustic pressure to the surface vibration is usually much stronger than the turbulent pressure, especially in the acoustic coincidence frequency range. The coupling is determined by the spatial matching between the pressure and the vibration which can be described by the wavenumber spectra. This paper uses measured vibration modes of a vehicle window to determine the coupling to both acoustic and turbulent pressure fields and compares these to the results from an SEA model. The interior acoustic intensity radiating from the window during road tests is also used to validate the results.
2017-06-05
Technical Paper
2017-01-1886
Siwen Zhang, Jian Pang, Jun Zhang, Zhuangzhuang Ma, Xiaoxuan Zhang, Congguang Liu, Lihui Deng
In this paper, the subjective evaluation method for the air-borne sound insulation performance of vehicle body in reverberation room is developed and investigated. To improve the credibility of the traditional subjective evaluation methods for the air-borne sound insulation, the test vehicles are placed in the reverberation room and exposed in the homogeneous reverberation sound field. The stationary vehicle's interior noise is recorded by using a digital artificial head. The noise testing method in reverberation room demonstrates more credible than the traditional methods based on the standard deviation analysis of vehicle external fields. With paired comparison scoring method, the recorded interior noises of six different vehicles are replayed and evaluated subjectively by 22 appraisers in the sound quality room. Kendall's correlation coefficient and circular error rates are introduced to check the consistency and correctness of the appraisers' evaluation scores.
2017-06-05
Technical Paper
2017-01-1852
Satyajeet P. Deshpande, Pranab Saha, Kerry Cone
Most of NVH related issues start from the vibration of structures where often the vibrations at resonance radiates the energy in terms of sound. This phenomenon is more pragmatic at low frequencies. This paper discusses a case study where different viscoelastic materials were evaluated on a bench study and then carried on to system level evaluation. A steel panel with a glazing system was used to study both airborne and structureborne noise radiation. System level studies were carried out using experimental modal analysis to shift and tune the mode shapes of the structure using visco-elastic materials with appropriate damping properties to increase the sound transmission loss. The paper discusses the findings of the study where the mode shapes of the panel were shifted and resulted in an increase in sound transmission loss and eventually resulted in reduced sound level in the cabin interior.
2017-06-05
Technical Paper
2017-01-1855
Ramakanta Routaray
The basic function of a motorcycle frame is somewhat similar to that of the skeleton in the human body, i.e. to hold together the different parts in one rigid structure. One of the major benefits (for a motorcycle enthusiast) of using an advanced frame design lies in the sporty handling characteristics of the bike. A well designed frame can add to the joy of riding a motorcycle as the bike would feel more stable, effortless, and confident around corners, in straight lines and while braking. A well approved modeling techniques or adequate guide line principles have to be followed while designing the body and chassis in order to achieve the vibration within control. This paper depicts a methodological right approach to model the body and chassis of a two wheeler in order to control noise and vibration of the body and chassis.
2017-06-05
Technical Paper
2017-01-1849
Laurent Gagliardini, Romain Leneveu, Aurélien Cloix, Alexandre Durr
The door response to audio excitation contributes to the overall performance of the audio system on several items. First, acting as a cabinet, it influences the loudspeaker response. Second, due to the door inner panel radiation, the radiated power is disturbed. A third effect is the regular occurrence of squeak and rattle, that will not be considered at this stage. Design issues regarding these attributes are numerous, from the loudspeaker design to door structure and trim definition. Modeling then appears as an unavoidable tool to handle the acoustic response of the loudspeaker in its actual surrounding.
2017-06-05
Journal Article
2017-01-1765
Albert Allen, Noah Schiller, Jerry Rouse
Corrugated-core sandwich structures with integrated acoustic resonator arrays have been of recent interest for launch vehicle noise control applications. Previous tests and analyses have demonstrated the ability of this concept to increase sound absorption and reduce sound transmission at low frequencies. However, commercial aircraft manufacturers often require fibrous or foam blanket treatments for broadband noise control and thermal insulation. Consequently, it is of interest to further explore the noise control benefit and trade-offs of structurally integrated resonators when combined with various degrees of blanket noise treatment in an aircraft-representative cylindrical fuselage system. In this study, numerical models were developed to predict the effect of broadband and multi-tone structurally integrated resonator arrays on the interior noise level of cylindrical vibroacoustic systems.
2017-06-05
Journal Article
2017-01-1806
Laurent Gagliardini
The input mobility is a crucial structural parameters regarding vibro-acoustic design of industrial objects. Whatever the frequency range, the vibrational power input into a structure –and consequently the average structural-acoustic response- is governed by the input mobility. When packaging structure-borne noise sources, the knowledge of the input mobility at the source connection points is mandatory for noise control. The input mobility is classically computed at the required points as a specific Frequency Response Function. During an industrial design process, the choice of connection points requires an a priori knowledge of the input mobility at every possible location of the studied structure-borne source, ie a mapping of the input mobility. The classical FRF computation at every Degree Of Freedom (DOF) of the considered structure would lead to consider millions of load cases which is beyond current computational limits.
2017-06-05
Technical Paper
2017-01-1830
Thomas Haase, Henning Bühmann, Martin Radestock, Hans Peter Monner
Due to the strengthened CO2 and NOX regulations future vehicles has to be lightweight and efficient. But, lightweight structures are prone to vibrations and radiate sound efficiently. Therefore, an active approach for reducing sound radiation from structures is the active structural acoustic control (ASAC). Since the early 90’s, several theoretical studies regarding ASAC systems were presented, but only very little experimental investigations can be found for this alternative to passive damping solutions. The theoretical simulations show promising results of ASAC systems compared to active vibration control approaches. So, for that reason in this paper an experiment is conducted to investigate the performance of an ASAC system in the frequency range up to 600 Hz. A regular sensor grid of 24 accelerometers that are interconnected to establish six radiation signals is applied to an aluminum plate.
2017-06-05
Journal Article
2017-01-1876
Weiyun Liu, David W. Herrin, Emanuele Bianchini
Microperforated panel absorbers are best considered as the combination of the perforate and the backing cavity. They are sometimes likened to Helmholtz resonators. This analogy is true in the sense that they are most effective at the resonant frequencies of the panel-cavity combination when the particle velocity is high in the perforations. However, unlike traditional Helmholtz resonators, microperforated absorbers are broader band and the attenuation mechanism is dissipative rather than reactive. It is well known that the cavity depth governs the frequency bands of high absorption. The work presented here focuses on the development, modeling and testing of novel configurations of backing constructions and materials. These configurations are aimed at both dialing in the absorption properties at specific frequencies of interest and creating broadband sound absorbers. In this work, several backing cavity strategies are considered and evaluated.
2017-06-05
Journal Article
2017-01-1825
Takenori Miyamoto, Hiroshi Yokoyama, Akiyoshi Iida
Intense tonal noise often radiates from flows around a trailing edge with an upstream kink shape such as found in an automobile bonnet, where fluid-acoustic interactions occur. It was clarified that the tonal sound became intense at a specific angle of the kink. Moreover, in order to reduce this noise, the flow was controlled by a dielectric barrier discharged plasma actuator (PA), which was attached around the kink shape. The flow and sound pressure were measured by a hot-wire anemometer and a microphone in a low-noise wind tunnel. In the flow around the model without control by the PA, vortices are shed in a separated flow between the kink and the trailing edge, and acoustic waves are radiating due to the interference of vortices with the wall. Measured coherent output power (COP) based on the simultaneous measurement of velocity fluctuations and far-field sound pressure shows that the velocity fluctuations near the trailing edge are related with the tonal acoustic radiation.
2017-06-05
Technical Paper
2017-01-1812
Steven Sorenson, Gordon Ebbitt, Scott Smith, Todd Remtema
In an effort to reduce mass, future automotive bodies will feature lower gage steel or lighter weight materials such as aluminum. An unfortunate side effect of lighter weight bodies is a reduction in acoustic transmission loss (TL). For barrier based systems, as the total system mass (including the sheet metal, decoupler, and barrier) goes down the transmission loss is reduced. If the reduced surface density from the sheet metal is added to the barrier, however, performance can be restored (though, of course, this eliminates the mass savings). In fact, if all of the saved mass from the sheet metal is added to the barrier, the TL performance may be improved over the original system. This is because the optimum performance for a barrier based system is achieved when the sheet metal and the barrier have equal surface densities. That is not the case for standard steel constructions where the surface density of the sheet metal is higher than the barrier.
2017-06-05
Journal Article
2017-01-1813
James M. Jonza, Thomas Herdtle, Jeffrey Kalish, Ronald Gerdes, Taewook Yoo, Georg Eichhorn
The aerospace industry has employed sandwich composite panels (stiff skins and lightweight cores) for over fifty years. It is a very efficient structure for rigidity per unit weight. 3M has developed novel thermoplastic composite panels that may be heated and shaped by compression molding or thermoforming with cycle time commensurate with automotive manufacturing lines build rates. These panels are also readily recycled at the end of their service life. As vehicles become lighter to meet carbon dioxide emission targets, it becomes more challenging to maintain the same level of quietness in the vehicle interior. Panels with interconnected honeycomb cells and perforations in one skin have been developed to absorb specific noise frequencies. The absorption results from a combination of Helmholtz resonators and quarter wave destruction interference effects.
2017-06-05
Technical Paper
2017-01-1814
Todd Tousignant, Kiran Govindswamy, Vikram Bhatia, Shivani Polasani, W Keith Fisher
The automotive industry continues to develop new powertrain and vehicle technologies aimed at reducing overall vehicle level fuel consumption. Specifically, vehicle light weighting is expected to play a key role in helping OEM’s meet fleet CO2 reduction targets for 2025 and beyond. Corning’s Gorilla® Glass Hybrid laminate solution offers more than 30% weight reduction compared to conventional automotive laminate. Additionally, Gorilla Glass Hybrid laminates provide improved toughness, better optics, and enables better vehicle dynamics by lowering the vehicle center of gravity. Although thin glazing offers multiple advantages, glazing weight reduction leads to an increase in transmission of sound through the laminates for certain frequencies. This paper documents a study that uses a systematic test-based approach to understand the sensitivity of interior vehicle noise behavior to changes in acoustic attenuation driven by installation of lightweight glass.
2017-04-24
WIP Standard
J1330
The purpose of this SAE Information Report is to list and explain major equipment, instrumentation, and procedure variables which can affect inter-laboratory differences and repeatability of photometric measurements of various lighting devices listed in SAE Technical Reports. The accuracy guidelines listed in the report are for the purpose of controlling variables that are not a direct function of the lighting device being measured. The control of these individual variables is necessary to control the overall accuracy of photometric measurements. These accuracy guidelines apply to the measurement of the luminous intensities and reflected intensities of devices at the specified geometrically distributed test points and areas. These guidelines do not apply to photometric equipment used to measure license plate lamps.
2017-04-18
WIP Standard
AS21240A
Scope unavailable.
2017-04-18
WIP Standard
AS21241A
Scope unavailable.
2017-04-17
Article
Audi reveals details of the structural technology of its upcoming A8 as Audi and Porsche Chairmen pledge closer co-operation.
CURRENT
2017-04-17
Standard
J361_201704
This SAE Recommended Practice applies to parts and materials used in vehicle manufacture which are intended to be acceptable color matches to a specified standard. This document is intended for use with parts or materials which are opaque or nearly so. Materials covered by this document include topcoat paint finishes, interior soft trim, interior and exterior hard trim, and exterior film and flexible trim. This practice requires judgments by observers with a minimum of normal color vision and preferably superior as rated with the FM-100 Hue Test as specified in ASTM E1499, Guide for Selection, Evaluation, and Training of Observers.
2017-04-04
WIP Standard
AS8943A
This standard covers plain and flanged sleeve bearings which are self-lubricating by incorporating polytetrafluoroethylene (PTFE) in a liner in the bore for use in a temperature range of -65 to +250 ˚F (-54 to +121 °C).
2017-04-02
WIP Standard
J974
This SAE Standard covers the general requirements and the test requirements for a flashing warning lamp for agricultural equipment.
2017-03-28
Technical Paper
2017-01-1300
Raj Jayachandran, Bhimaraddi Alavandi, Matt Niesluchowski, Erika Low, Yafang Miao, Yi Zhang
Abstract An engine cooling system in an automotive vehicle comprises of heat exchangers such as a radiator, charge air cooler and oil coolers along with engine cooling fan. Typical automotive engine-cooling fan assembly includes an electric motor mounted on a shroud that encloses the radiator core. One of main drivers of fan shroud design is Noise, Vibration, and Harshness (NVH) requirements without compromising the main function of airflow for cooling requirements. In addition, there is also a minimum stiffness requirement of fan shroud which is often overlooked in arriving at optimal design of it. Low Speed Damageability (LSD) assessment of an automotive vehicle is about minimizing the cost of repair of vehicle damages in low speed crashes. In low speed accidents, these fan motors are subjected to sudden decelerations which cause fan motors to swing forward thereby damaging the radiator core. So designing fan shroud for low speed damageability is of importance today.
2017-03-28
Technical Paper
2017-01-1468
Do Hoi KIm
Previous work identified a relationship between vehicle drop and dummy injury under the high-speed frontal impact condition [1]. The results showed that vehicle drop greater than 60mm made the dummy injury worse. Moreover, that work identified the front side member as the crucial part affecting the vehicle drop. In this study, the body structure mechanism was studied to reduce vehicle drop by controlling the front side member, shotgun, and A-pillar. By analyzing full vehicles, it was recognized that the arch shape of the front side member was very important. Furthermore, if the top of the arch shape of front side member, shotgun, and A-pillar were connected well, then the body deformation energy could lift the lower part of A-pillar, effectively reducing vehicle drop. This structure design concept is named “Body Lift Structure” (BLS). The BLS was applied to B and C segment platforms. Additionally, a “Ring” shape was defined by the front side member, dash panel, and A-pillar.
2017-03-28
Technical Paper
2017-01-1451
Jan Vychytil, Jan Spicka, Ludek Hyncik, Jaroslav Manas, Petr Pavlata, Radim Striegler, Tomas Moser, Radek Valasek
Abstract In this paper a novel approach in developing a simplified model of a vehicle front-end is presented. Its surface is segmented to form an MBS model with hundreds of rigid bodies connected via translational joints to a base body. Local stiffness of each joint is calibrated using a headform or a legform impactor corresponding to the EuroNCAP mapping. Hence, the distribution of stiffness of the front-end is taken into account. The model of the front-end is embedded in a whole model of a small car in a simulation of a real accident. The VIRTHUMAN model is scaled in height, weight and age to represent precisely the pedestrian involved. Injury risk predicted by simulation is in correlation with data from real accident. Namely, injuries of head, chest and lower extremities are confirmed. Finally, mechanical response of developed vehicle model is compared to an FE model of the same vehicle in a pedestrian impact scenario.
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